Automatic telephone system



June 30, 1925.

F. T. MADSEN AUTOMATIC TELEPHONE SYSTEM z/ 8 v f f dw' J fzzzrezzfar Fred 7? 12755752-22 Patented June 30, 1925.

UNITED STATES I v 1,544,330 PATENT OFFICE.

FRED T. MADSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC GOM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed June 30, 1919.

T u all whom it may concern:

Be it known that I, FRED T. MADSEN, a

citizen of the United States of America, and

a resident of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to an automatic telephone system and more specifically to an improved dialling circuit for use in controlling an automatic switch from a telephone line and is especially adapted for use in a rural or community automatic exchange system, in which the lines over which it is desired to operate the automatic switches are often of high resistance and are badly put up so as to have a poorer insulation than the ordinary city telephone line and therefore are more liable to have leakage to ground. It is therefore necessary in such systems to provide, in place of the usual double wound line relay for the switches, a more efficient and more positive acting line relay and at the same time to maintain a balanced talking circuit with the proper impedance across the same in the battery feed to give good talking qualities.

In order to accomplish the above result I have provided a line relay or controlling relay for an automatic switch which is normally and during talking, bridged across the line in the usual manner with an em pedance on each side of the talking and operating battery, and which is switched over during the transmission of impulses by switching devices to a different connection with the line and battery to provide a more efiicient dialling circuit. Further details and a more detailed description may be had from the following detailed specification.

In the drawing I have shown my im proved dialling circuit in connection with a selector repeater B which I have shown as individual to a calling line A. It is to be understood that there may be any number of switches inserted between the line A and the switch B, such as a line switch and any number of selectors, without in any way affecting the operation of the switch B or the dialling circuit and also that this improved dialling circuit may be used as well on any type of two wire switch such as a selector or a connector without departing from the spirit of my invention.

Serial No. 307,560.

When the subscriber at station A removes his receiver to initiate a call, a circuit is completed from ground through the lower. windmg of the line relay 2 of switch B:

through sprin 3 and 4, windin 5 of repeating coil 5? springs 6 and ,to and through the talln'ng equipment of line A, springs 8 and 9, winding 10 of coil C, springs 11 and 12, upper winding of relay 2 and springs 13 and 14 to battery. Relay 2 energizes over this circuit and closes the springs 15 in the talking circuit and also opens springs 16 and 17 and closes springs 17 and 18 in the circuit of slow relay 19. The relay 19 energizes to prepare certain circuits at springs 20, prepares the circuit of the vertical magnet 21 and relay 22 at springs 23 and 24, and opens the springs 25 in the private normal conductor in series with relay 26. The closure of springs 23 and 24: also prepares a circuit for the slow relay 27 which controlsthe switching over of the line relay 2 to the new dialling circuit.

Now as soon as the calling subscriber operates his calling device for the first digit of the called number, relay 2 responds to this digit to operate relay 22 and to cause magnet 21 to operate to step the wipers of the switch to a desired level. The circuit of relay 22 and magnet 21 extends from ground through contacts 17 and 16, closed intermittently, springs 28 and 29, springs 24 and 23, and relay 22 and magnet 21 to battery.

Relay 22 being slow acting remains energized during successive impulses to hold re lay 30 energized from ground through springs 20, springs 31 and 32, and off normal springs 33 after the switch takes its first vertical step. Relay 27 energizes at the first deenergization of line relay 2 to switch the connections of the line relay 2 with regard to its energizing circuit. While relay 27 is energized, that is, while the relay 2 continues to respond to impulses, the circuit of relay 2 is as follows: Ground through its lower winding, springs 3 and 34, through the upper winding of relay 2, springs 13 and 35, winding 5 of repeating coil C, springs 6 and 7, to and through the line A, springs 8 and 9, winding 10, springs 11 and 36, and resistance 37 'to battery. Thus it will be seen that the line relay 2 has both of its windings connected in series connected as in the first instance with one winding to ground and the other to battery, then it will be seen that any leak to ground would prevent the line relay from falling back instantly when the line is opened and would therefore materially afi'ectthe operation of relay 2 in controlling the magnets.

Relay 27 of course opens the original connections of line relay 2 .at springs 13 and 14,

at springs 3 and 4, and at sprin s 11 and 12.

Now, as soon as the impulses ibr this digit cease, relay 27 falls back to restore the line relay 2 to its original connection. As soon as rela 22 falls back a circuit is closed from groun through springs 20, springs 31 and 38, springs 39, relay 30 being energized, and through rotary magnet 40 to battery. Magnet 40 energizes to step the wipers to the first set of contacts in the selected level and also opens springs 41 to open the circuit of relay 30 which is now also open at springs 31 and 32. As relay 30 falls back the circuit of magnet 40 is in turn opened at springs 39 and magnet 40 falls back to close the sprin s .41. Should the trunk connected to this rst set of contacts be busy and should a ground therefore be connected to test wiper 42, this ground will operate to short circuit the relay 43 in the series circuit from ground through springs 20, relay 43, springs 41, springs 33 and relay 30 to battery, and will cause relay 30 to again energize and close the circuit of magnet 40 at springs 39. This alternate operation of relay 30 and magnet 40 continues until an idle trunk line is reached which has no ground present on its test contact. At this time relay 43, being no longer shorted out, energizes over the series circuit withrelay 30 and by its high resistance prevents the energization of relay 30. Relay 43, upon energizing, switches the private wiper 42 through springs 44 and 45 so that relay 43 cannot again be shorted out by ground on the private.

As soon as the wipers come to rest on the contacts of an idle trunk line, a circuit is completed for'the line relay of whatever switch (selector or connector) may be connected thereto in series with the wipers 46 and-47 and the springs 15 of relay 2. Thus it will be seen that any further operation of the line relay 2 in response to further sets of impulses from the calling line does not control the relay 22 or magnet 21 due to the opening of that circuit at springs 28 and 29 of relay 43, but only by means of the springs 15 controls the circuit of the line relays of the switches ahead. Also it will be seen that the closure of springs 28 and 48 by relay 43 holds the relay 27 under control of relay 2 so that said line relay 2 always controls relay 27 to vary the connections of its own windings to give the improved dialling circuit either when operating its own wipers or operating the line rclays of the switches ahead.

When the line A is called and a connector switch makes connection with the normal conductors 50, 51 and 52 then a ground is connected to conductor 52 through spring 25 and its back contact to relay 26 which energizes to open springs 53 and to connect the alternating current relay 54 across the conductors 50 and 51. Relay 54 responds to ringing current from the connector to energize relay- 55 which connects conductors 50 and 51 to the line A to cause the ringing current to signal the line A, and after the subscriber on line A responds and cuts off the ringing current then conversation may be carried on from the line A to the calling line through the medium of repeating coil C.

It will be seen therefore, that I have provided a; novel and eflicient dialling circuit for an automatic switch which although shown in connection with a selector repeater of somewhat special construction, may be as well applied to any standard type of connector switch.

Having fully described and ascertained the features and aspects of my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a trunk line, an automatic switch for said trunk line having a line relay responsive to impulses of current to control the various operations of the switch, a pair of windings for the relay normally connected in bridge of said trunk line and with .a battery connected between the-two windings in said relay in said bridge, and means for varying the connections of said relay to the trunk line during impulses so that both windings are connected between one side of the trunk line and the battery.

2. In a telephone system, a trunk line, an automatic switch for said trunk line having a line relay responsive to impulses of current to control the various operations of the switch, a pair of windings for the relay normally connected in bridge of said trunk line and with a battery connected between the two windings in said relay in said bridge, and means for varying the connections of said relay to the trunk line during impulses so that both windings are connected between one side of the trunk line and the grounded side of the battery.

3. In a telephone system, a line, an automatic switch for said line, a calling device for the line, a line relay for the switch in series with said line and responsive to impulses from the calling device to control the operations of the switch, said line relay having a pair of windings normally connected in bridge of the line with a grounded battery interposed between the windings of the relay in series therewith, means responsive to the first impulse for connecting both windings of the relay on the grounded side of the battery in said bridge, and a resistance on the other side of the battery in said bridge.

4. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected between one terminal of said battery and one side of the line and another leg including another relay coil connected between the other terminal of the battery and the other side of the line, and means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge.

5. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said linehaving one leg including one relay coil connected be-- tween one terminal of said battery and one side of the line and another leg including another relay coil connected between the other terminal of the battery and the other side of the line, and means for switching one of said coils from one leg of said bridge and connectin it in the other leg of the bridge between tile line and the other relay coil.

' 6. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected between one terminal of said batter and one side of the line and another leg inc uding another relay coil connected between the other terminal of the battery and the other side of the line, and automatic means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge.

7. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected between one terminal of said battery and one side of the line and another leg including another relay ooil connected between the other terminal'of the battery and the other side of the line, and automatic means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge between the line and the other relay coil.

8. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one side of the line and another leg includinganother relay coil connected between the other terminal of the battery and the other side of the line, and means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge, said coils connected on each side of the battery while talking and on one side of the battery while the switch is being operated.

9. In a telephone system, a line, an automatic switch for said line, a battery, ,a controlling bridge across said line having one leg including one relay coil connected between one terminal of said battery and one side,of the line and another leg including another relay coil connected between the other terminal of the battery and the other side of the line, and means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge between the line and the other relay 0011, said coils connected on each side of the battery while talking and on one side of the battery while the switch is being operated.

10. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected between one terminal of said battery and one side of the line and another leg including another relay coil connected between the other terminal of the battery and the other side of the line, and automatic means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge, said coils connected on each side of the battery while talking and on one side of tihe battery while the switch is being oper-- ate 11. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected be.- tween one terminal of said battery and one side of the line and another leg including another relay coil connected between the other terminal of the battery and the other side ofthe line, and means for switching one of said coils from one leg of said brid e and connecting it in the other leg of the bridge, said coils being connected in the latter manner on one side of the battery only while impulses are being delivered to the switch.

12. In-a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line having one leg including one relay coil connected between one terminal of said battery and one side of the line and another leg including another relay coil connected. between the other terminal of the battery and the other side of the line, and means for switching one of said coils from one leg of said bridge and connecting it in the other leg of the bridge, and a slow relay controlled jointly by said relay coils to automatically swltch the connections of said coils in the manner described.

13. In a telephone system, a line, a battery, a calling device and an automatic progressively movable switch; a relay having two windings, means for connectlng said relay with one winding betweenone terminal of the battery and one side of the line, and the other winding between the other terminal of the battery and the other side of the line, and also for switching both of said windings in series between one side of the line and battery; said first arrangement for feeding current for talking purposes to the line and the second arrangement for operating said relay from said calling device for operating said automatic switch to establish. a connection between two lines.

14. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line, one leg of said bridge including a relay coil connected from one terminal of said battery to one side of the line, another leg including another relay coil connected to the opposite terminal of the battery and the other side of the line, and means for switching-the connections of said coil and the line to connect the two coils in series between one terminal of said battery and one conductor of said line.

15. In a telephone system, a lme, an auto-- matic switch for said line, a battery, a controlling bridge across said line, one leg of said bridge including a relay coil connected from one terminal of said battery to one side of the line, another leg includin another relay coil connected to the opposite terminal of the battery and the-other side of the line, and automatic means for switching the connections of said coil and the line to connect the two coils in series between one terminal of said battery and one conductor of said line and to connect the other terminal of said battery-to the other conductor of said line.

16. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across said line, one leg of said bridge including a relay coil connected from one terminal of said battery to one side of the line, another leg including another relay coil connected to the opposite terminal of the battery and the other side of the line, and means for switching the connections of said coil and the line to connect the two coils in series between one terminal of said battery and one conductor of said line only while impulses are being sent.

17. In a telephone system, a line, an automatic switch for said line, a battery, a 0on trolling bridge across said line, one leg of said bridge including a relay coil connected from one terminal of said battery to one side of the line, another leg including another relay coil connected to the opposite terminal of the battery and the other side of the line, means for switching the connections of said coil and the line to connect the two coils in series between one terminal of said battery and one side of said line and to connect the other terminal of said battery to the other side of said line, and means for replacing the normal connections of said bridge.

18. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across two conductors of said line, one leg of said bridge including a relay winding connected from one terminal of said battery to one conductor of said line, another leg of said bridge including another winding connected to the opposite terminal of said battery and the other of said conductors, a circuit including said line conductors for energizing said relay windings, means for producing interruptions in said circuit, a resistance, and automatic means for connecting a terminal of said battery through said resistance to one conductor of said line and for maintaining such connection continuously while said interruptions are being produced.

19. In a telephone system, a line, an automatic switch for said line, a battery, a controlling bridge across two conductors of said line, one leg of said bridge including a relay winding connected from one terminal of said battery to one conductor of said line, another leg of said bridge including another winding connected to the opposite terminal of said battery and the other conductor of said line, means for sending impulses line independent of both of said windingswhile maintaining the other terminal of said battery connected to the other conductor of said line through one of said windings.

20. In a telephone system, a line terminating in an automaticswitch, a battery, a line relay for said switch, two windings for said line relay, one terminal of one winding being connected to one conductor of said line, one terminal of the other winding being connected to the other conductor of said line, the remaining terminals of said windings being connected to opposite terminals of said battery, means for sending impulses to said line relay, and means operative while impulses are being sent for connecting one terminal of said battery to one of said line conductors independent of either winding of said relay.

21. In a telephone system, a line, an auto matic switch, means for controlling the operation of said switch comprising two relay coils, a bridge across said line including both relay coils and the battery, and means for altering the bridge circuit so as to change the location of said battery with respect to said relay coils.

22. In a telephone system, a line, an automatic switch, a double wound line relay in said switch, a battery, a bridge across the line including both windings of said relay and the said battery, and a relay for altering the bridge circuit so as to change the location of said battery with respect to the relay windings.

23. In a telephone system, a line, an automatic switch, a double wound line relay in said switch, a battery, 2. bridge across the line including both windings of said relay and the said battery, a second relay controlled by said line relay, and means con trolled by said second relay for altering the bridge circuit so as to change the relative positions of the relay windings and said battery.

24. In a telephone system, a line, an automatic switch, a double wound line relay in said switch, a battery, a bridge across the line including both windings of said relay and the said battery, a slow acting relay maintained energized by said line relay when the said line relay responds to impulses received over said line, and means controlled by said slow acting relay for altering the bridge circuit so as to change the relative posltlons of the relay windings and said battery.

25. In a telephone system, a line, an automatic switch, a double wound line relay in said switch, a battery, a bridge across the line including both windings of said relay and the said battery, and means controlled by said line relay when the same responds to impulses received over the said line for altering the bridge circuit so as to include the same elements in a difi'erent order.

26. In a telephone system, a. line, an automatic switch, a line relay for said switch,

a, battery having both poles normally co-n nected to the line through windings of said line relay, and means controlled by said line relay responsive to impulses received over the line for altering the circuits so that the battery is connected to one conductor of the line independent of the relay and the relay is connected to the other conductor of the 27. In a telephone system, a subscribers line, an automatic switch for extending said line when calling, a repeating coil individual to said line and inserted between the line and said switch, normal conductors for use in extending connections to said line when the same is called, said normal conductors extending to said switch whence they may be connected to said line inductively by means of said repeating coil, a relay permanently bridged across said normal conductors and responsive to ringing current received thereover, a second relay controlled by said first relay, and contacts on said second relay for disconnecting the line from said repeating coil and for connecting said line direct to said normal conductors.

28. In a telephone system, a subscribers line, an automatic switch for ext-ending said line when calling, a repeating coil individual to said line and inserted between the line and said switch, normal conductors for use in extending connections to said line when the same is called, a relay energized when the line is called for extending said normal conductors to said switch, there being an open connection remaining between one of said conductors and said repeating coil, a second relay responsive to ringing current received over said normal conductors, a third relay controlled by said second relay, contacts on said third relay for disconnecting the line from said repeating coil and for connecting the line direct to said normal conductors, and a fourth relay energized by the called subscriber over said line when the ringing ceases to close said open connection and complete the talking circuit.

29. In a telephone system, a subscribers line, a selector repeater individual to said I line, a repeating coil inserted between said line and switch, a line relay in said switch connected in series with the windings on the line side of said repeating coil and controlled over said line, contacts on said line relay for operating the switch to extend a connection to another switch, other con-- tacts on said line relay connected in series with the windings on the switch side of said repeating coil for repeating impulses over the extended connection, and means for rendering the said switch operating contacts ineffective while the other said contacts are being operated to repeat impulses.

Signed by Ine-at Chicago, Cook County, Illinois, this 28th day of June, 1919;

FRED T. MADSEQN. 

